The present invention relates to digital video systems, and more particularly, to systems for reducing the required data rate without sacrificing picture quality.
In digital broadcast systems, the effective use of the data rate is of primary importance. A reduction in data rate reduces both video tape usage and the necessary transmission bandwidth; however, this must be accomplished while maintaining broadcast quality pictures.
One method of data reduction which is presently under consideration is the process of sub-Nyquist sampling, such as is disclosed in the paper "Sub-Nyquist Encoded PCM NTSC Color Television" by John P. Rossi in the book "Digital Video," a review of SMPTE papers, and in the article by Leonard S. Golding, "Frequency Interleaved Sampling of a Color Television Signal," IEEE Transactions on Communication Technology, Volume COM-19, page 972, December, 1971. These sub-Nyquist type systems have samples that lie along diagonals with the distance between the diagonals being greater than the horizontal distance between samples. Since the smaller the distance between samples the greater the resolution, these systems are capable of increasing the horizontal resolution which is available at a given data rate, but at the expense of the diagonal resolution.
It is therefore desired to have a data rate reduction arrangement for digital television signals that does not cause any sacrifice in picture quality.